Keithley 2015 THD Multimeter, Oscilloscope Myths, and Test Gear Buying Traps: 7 FAQs from the Trenches

I've been specifying test equipment for R&D labs since 2017. And I've made expensive mistakes. The kind that make you sit in your car and just stare at the dashboard.

So here are the questions I wish someone had answered before I clicked “Add to Cart.” Some are simple mix-ups. Others are cost traps. All worth a minute.

What you'll find here

• Is Keithley the right brand for my bench?
• What's the Keithley 2015 THD multimeter for?
• Does Keithley make an oscilloscope?
• Why do people search for "337 clamp meter" with Keithley?
• What does "12 multimeter" mean?
• Where can I buy ifm inductive sensors online?
• Why should I compare total cost, not list price?

Is Keithley the right brand for my bench?

Look, I'm not a brand evangelist. I've bought Fluke, Keysight, and Keithley for different jobs. But for low-level electrical measurements—high resistance, small currents, semiconductor curves—Keithley is a solid default. The 6.5-digit resolution on the DMM6500 or the 2015 can see signals that a 3.5-digit handheld completely misses.

That doesn't mean you need one for every channel. If you're just logging temperatures, a low-cost DAQ might do. But if you're characterizing components that cost $200 each, precision is not a luxury. It's necessity.

What's the Keithley 2015 THD multimeter for?

The 2015 is a 6.5-digit bench DMM with built-in harmonic analysis. It measures THD and THD+N over the audio band, roughly 20 Hz to 20 kHz. That's a niche feature you don't get on a standard DMM.

I once recommended a standard DMM to a team doing audio amplifier verification. It looked fine on paper—enough bandwidth, enough resolution. Two weeks later, we found they needed THD. The result? A $900 rework and a one-week delay. Not the instrument's fault. Mine, for not asking the right question.

Per Keithley's published datasheet, the 2015's THD range is 0.01% to 100%. That's enough for most production audio tests. If you're doing high-end design, you may want a dedicated analyzer, but the 2015 is a workhorse.

Does Keithley make an oscilloscope?

No. Keithley does not make oscilloscopes. I keep seeing "keithley oscilloscope" in search logs, and the answer is always the same.

Why the confusion? Because Tektronix owns Keithley, and Tektronix does make scopes. So when you search for a Keithley scope, Google sometimes shows Tektronix models. They're good scopes. But they're not Keithley.

What to do instead: for high-speed waveform analysis, buy a Tektronix or another scope. For slow trends and data logging, a Keithley DAQ plus a DMM is often a better fit. Different tools.

Why do people search for "337 clamp meter" with Keithley?

There is no Keithley 337 clamp meter. The 337 is actually a Fluke clamp meter—a solid one, with 1000 A AC/DC current measurement as I recall from the spec sheet.

This misunderstanding cost me once. A requisition said "Keithley 337." We almost ordered it as is. I'm glad I asked. The engineer had seen "337 clamp meter" in a vendor quote and assumed it was Keithley because the rest of the bench was Keithley. Lesson: verify the brand, not just the model number.

If you need a clamp meter, Fluke is a good choice. But don't expect it to talk over TSP or GPIB with your Keithley gear. It's a handheld tool.

What does "12 multimeter" mean?

This is a search phrase I see often: "12 multimeter." I suspect it's a mangled version of "6 1/2 digit multimeter."

Here's why: a 6.5-digit meter has 6 full digits plus a half-digit at the front. People write that as "6 1/2", and the "1/2" can end up as "12" in a search. Or maybe they want a 12-function handheld. Both exist.

If you need a precision bench meter, search for "6.5 digit multimeter" instead. That gets you to Keithley, Keysight, Fluke, and others.

Between you and me, a 6.5-digit instrument is overkill for basic electrician work. For lab characterization, it's appropriate. Don't buy one because you think more digits sound impressive.

Where can I buy ifm inductive sensors online?

Strange question for a Keithley page, but people search it, so let's get it done.

For genuine ifm inductive sensors, buy from a known distributor: Digi-Key, Mouser, AutomationDirect, or directly from ifm's site. Prices change monthly, so I won't quote numbers.

TCO point: a gray-market sensor may cost a few dollars less, but I've been burned. In 2023, I bought a batch from a third-party warehouse. Two of three died within a month. We spent more on troubleshooting than we saved. Now I stick with authorized distributors.

Why should I compare total cost, not list price?

The $500 quote is never $500. The $650 quote is often cheaper when you count the full lifetime.

I now write a TCO checklist for each purchase. It includes:

• Calibration fees (annual for most lab gear)
• Warranty and repair response time
• Software, cables, and integration costs
• Training time for your team
• Cost of a wrong measurement: rework, scrap, delays

Case in point: a used Keithley 2015 from a non-authorized reseller might be $900. But it often arrives without a calibration certificate. Sending it out costs $400 and eats two weeks. A new one from a distributor runs around $1,800 with calibration included. The TCO gap is smaller than you think.

I still kick myself for the time I bought a $250 bench DMM instead of a calibrated Keithley. It was off by 0.4% at 10 V, which ruined a week of prototype testing. We missed a deadline. The client used another lab. Stupid way to save $300.

Looking back, I should have calculated measurement risk before spending. At the time, the budget looked tight. In reality, a proper meter would have paid for itself in half a day.